Wobble motor microactuator for fine positioning and disk drive incorporating ...

United States Patent [w]

Fan et al.

US005805375A [ii] Patent Number: [45] Date of Patent:

5,805,375 Sep. 8, 1998

[54] WOBBLE MOTOR MICROACTUATOR FOR FINE POSITIONING AND DISK DRIVE INCORPORATING THE MICROACTUATOR

[75] Inventors: Long-Sheng Fan; Robert Edward

Fontana, Jr., both of San Jose, Calif.;
Tomotake Furuhata, Yokohama, Japan;
Timothy Clark Reiley, Los Gatos;
Hans Helmut Zappe, San Jose, both of
Calif.

[73] Assignee: International Business Machines
Corporation, Armonk, N.Y.

[21] Appl. No.: 703,111

[22] Filed: Aug. 22, 1996

Related U.S. Application Data

[63] Continuation of Ser. No. 284,334, Aug. 1, 1994, abandoned.

[51] Int. CI.6 G11B 5/596; H02N 1/100

[52] U.S. CI 360/78.12; 360/78.13;

360/78.04; 310/309; 310/82

[58] Field of Search 360/78.12, 78.13,

360/78.01, 78.04; 310/309, 308, 80, 82

[56] References Cited

U.S. PATENT DOCUMENTS

4,943,750 7/1990 Howe et al 310/309

5,041,932 8/1991 Hamilton 360/104

5,043,043 8/1991 Howe et al 156/645

5,079,653 1/1992 Gauthier et al 360/78.13

5,093,594 3/1992 Mehregany 310/82

5,172,287 12/1992 Ishida 360/78.12

5,180,940 1/1993 Paratte et al 310/40 MM

5,202,803 4/1993 Albrecht et al 360/97.02

5,339,206 8/1994 Takahashi 360/78.12

5,539,267 7/1996 Fan et al 360/99.08 X

OTHER PUBLICATIONS

S. C. Jacobsen et al., "The Wobble Motor: Design, Fabrication and Testing of An Eccentric-motion Electrostatic Microactuator", IEEE, 1989, pp. 1536-1546.

S. C. Jacobsen et al., "Design, Analysis, and Experimental Results for the Wobble Motor: An Eccentric-motion Electrostatic Microactuator", SPIE vol. 1167, Precision Engineering and Optomechanics, 1989, pp. 122-136. S. C. Jacobsen et al., "Micromotors Split Hairs", IEEE Potentials, Feb. 1991, pp. 12-15.

M. Mehregany et al., "Friction and Wear in Microfabricated Harmonic Side-drive Motors", 1990 IEEE Solid State Sensor and Actuator Workshop—Technical Digest, pp. 17-22. L. Paratte et al., "A Rigid Ring Electrostatic Harmonic Wobble Motor with Axial Field", 1991 IEEE International Conference on Solid-state Sensors and Actuators, pp. 890-893.

R. H. Price et al., "Field Analysis for the Electrostatic
Eccentric Drive Micromotor ('Wobble Motor')", Journal of
Electrostatics, vol. 28, 1992, pp. 7-38.

Primary Examiner—Aristotelis M. Psitos
Assistant Examiner—Larry T. Cullen
Attorney, Agent, or Firm—-Thomas R. Berthold

A microfabricated wobble motor with a positioning arm attached to the wobble motor rotor acts as a fine positioner with bidirectional movement. The primary application is a rotary actuator for the read/write head in a very small magnetic recording disk drive. An integrated head-arm assembly is attached at one end to the rotor of the wobble motor. The other end of the head-arm assembly has a head carrier that is maintained in contact with the disk. Head position error information is read from the disk and used to provide control signals to each of the stator elements. The stator elements are sequentially addressed by applying a voltage from a driver circuit. This causes the rotor to be electrostatically attracted to the activated stators, so that the rotor is movable bidirectionally. The read/write head can thus be moved bidirectionally to any of the data tracks on the disk and maintained on a desired data track for reading or writing data. The fine positioner also includes a digital control system where each of the stator elements is represented by an address, and the movement of the rotor is controlled by incrementing or decrementing the stator address in an address register.

5 Claims, 8 Drawing Sheets